There is a general desire to collect particulates in gas streams and for disposal or reuse. As one example, though this disclosure is not to be limited to oil refinery operations, in the area of oil refinery operations, one particular area of concern regarding catalyst retention in the circulating inventory of the reactor and regenerator.
The fluid catalytic cracking (FCC) process is well known and has undergone continuous improvement and remains the predominant methodology of gasoline production in many refineries. Generally, gasoline, as well as lighter products, is formed as the result of cracking heavier (i.e. higher molecular weight), less valuable hydrocarbon feed stocks such as gas oil. A general outline of the FCC process is provided below, although it is to be appreciated that the FCC process is a large and complex process involving many factors that are not addressed.
In its most general form, the FCC process involves use of a reactor that is closely coupled with a catalyst regenerator, followed by downstream hydrocarbon product separation. The catalyst regenerator collects spent catalyst having coke on the surface thereof, combusts the coke from the surface of the spent catalyst to refresh the catalyst, and returns the refreshed catalyst to the reactor. One specific feature of the FCC process is the continuous fluidization and circulation of large amounts of catalyst having an average particle diameter of about 50-100 microns, equivalent in size and appearance to very fine sand. For every ton of cracked product made, approximately 5 tons of catalyst are needed, thus highlighting the significance of the catalyst regenerator in the FCC process. Coupled with the need for a large inventory and recycle of a small particle diameter catalyst is the ongoing challenge to prevent this catalyst from exiting the reactor and/or catalyst regenerator system into effluent streams.
A fluidized-bed catalytic cracking plant can comprise a reactor vessel, a vertical reactor riser having an upper outlet which is in fluid communication with a separator system arranged in the reactor vessel, and a regenerator vessel. During normal operation, regenerated catalyst particles and hydro-carbonaceous feed are supplied to the inlet end of the reactor riser in which catalytic cracking of the feed takes place to form a mixture of gaseous product and catalyst particles. The mixture leaves the reactor riser at a high temperature of between 500 and 540° C. or higher. The mixture of gaseous product and catalyst particles is passed into the separator system where gaseous product is separated from catalyst particles. The gaseous product is removed from the upper end of the reactor vessel, and the catalyst particles are discharged to the lower part of the reactor vessel where they are stripped. Stripped catalyst particles are passed to the regenerator vessel where coke deposited on the particles during cracking is burnt-off at a high temperature to obtain combustion products and regenerated catalyst. The combustion products are removed from the upper end of the regenerator vessel and regenerated catalyst is re-used.
There remains a need for a compact separation assembly and improved efficiency of cyclone separators, in particular, creating a lower pressure drop across the dual stage separators due to fewer particle-contaminated gas flow directional changes in the particulate contaminated gas stream. The lower pressure drop provides for a greater compression ratio across a power recovery turbine and more horse power potential. The present disclosure provides solutions to the problems of cyclone separators and assemblies.
Other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and claims, taken in conjunction with the accompanying drawings and this background of the disclosure.